It looks very much like a mud dauber wasp which I recognize because of its petiole, the narrow abdominal segment that joins the rest of the abdomen to its thorax. You have seen its nest of mud on walls and fence posts. The holes to the cells of these nests are very narrow and I first thought this wasp was very silly to catch a prey that was too large.
Silly me, insects know what they are doing. The mud dauber wasp selects a specific kind of spider and can cram from ten to twenty paralyzed ones into a single cell with one egg.
This must be a ground-digger wasp. It has nests in the ground with cells big enough for katydids or the cicadas which they dig up for their young.
Glad I noticed.
What have you noticed today?